Opitz, M. F. (1994). Learning centers: Getting them started, keeping them going. Scholastic Professional Books.
Chicago-Zitierstil (17. Ausg.)Opitz, Michael F. Learning Centers: Getting Them Started, Keeping Them Going. New York [u.a.]: Scholastic Professional Books, 1994.
MLA-Zitierstil (9. Ausg.)Opitz, Michael F. Learning Centers: Getting Them Started, Keeping Them Going. Scholastic Professional Books, 1994.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.